my_leetcode/sql/q0175.md

175.组合两个表

原题链接

2021-07-16 10:18:48

SQL架构:

Create table Person (PersonId int, FirstName varchar(255), LastName varchar(255));
Create table Address (AddressId int, PersonId int, City varchar(255), State varchar(255));
Truncate table Person;
insert into Person (PersonId, LastName, FirstName) values ('1', 'Wang', 'Allen');
Truncate table Address;
insert into Address (AddressId, PersonId, City, State) values ('1', '2', 'New York City', 'New York');

表1: Person

列名	类型
PersonId	int
FirstName	varchar
LastName	varchar

PersonId 是上表主键

表2: Address

列名	类型
AddressId	int
PersonId	int
City	varchar
State	varchar

AddressId 是上表主键

题

编写一个 SQL 查询，满足条件：无论 person 是否有地址信息，都需要基于上述两表提供 person 的以下信息：

FirstName, LastName, City, State

Related Topics 数据库

👍 879 👎 0

解

SELECT `Person`.`FirstName`, `Person`.`LastName`, `Address`.`City`, `Address`.`State`
FROM `Person`
LEFT JOIN `Address`
ON `Person`.`PersonId`=`Address`.`PersonId`;